Troubleshooting of Zone-Selective Interlocking Test

Condition	Probable causes	Solutions
Isd/Ii and/or Ig LED not flashing on upstream circuit breaker when performing ZSI test.	Upstream circuit breaker not wired for ZSI configuration. Trip unit on upstream circuit breaker does not have power applied to it. Interface screen displays communication error. Upstream circuit breaker not wired for short time ZSI restraint. Upstream circuit breaker not wired for ground-fault ZSI restraint. MicroLogic 3.0 trip unit connected to the Service Interface. (MicroLogic 3.0 trip unit does not provide short-time or ground-fault protection.)	ZSI test cannot be performed. Connect and turn on auxiliary 24 V power source to upstream circuit breaker. Replace with new Service Interface. Check that pins of seven-pin test cable have not been bent, pushed in, pulled out or otherwise damaged. Refer to MicroLogic Trip Unit Compatibility to determine if test is applicable to trip units. If both upstream and downstream trip units are powered and trip indicator LEDs are not flashing, verify wiring between devices. Terminal Z1 from downstream trip unit must be connected to terminal Z3 of upstream trip unit. Terminal Z2 of downstream trip unit must be connected to terminals Z4 (for short time) and Z5 (for ground fault) of upstream trip unit. If wiring is correct and trip indicators do not flash while Service Interface is initiating ZSI test, then verify trip unit is not self-restrained. Use an ohmmeter to verify terminal Z3 is not shorted to terminals Z4 and/or Z5. All devices are factory-shipped in self-restrained configuration with Z3 shorted to Z4 and Z5. If system includes Restraint Interface Module (RIM) module, push-to-test button sends a ZSI test signal to upstream devices. For correct wiring and operation instructions, refer to the RIM Instruction Bulletin.

Condition

Probable causes

Solutions

Isd/Ii and/or Ig LED not flashing on upstream circuit breaker when performing ZSI test.

Upstream circuit breaker not wired for ZSI configuration.
Trip unit on upstream circuit breaker does not have power applied to it.
Interface screen displays communication error.
Upstream circuit breaker not wired for short time ZSI restraint.
Upstream circuit breaker not wired for ground-fault ZSI restraint.
MicroLogic 3.0 trip unit connected to the Service Interface. (MicroLogic 3.0 trip unit does not provide short-time or ground-fault protection.)

ZSI test cannot be performed.
Connect and turn on auxiliary 24 V power source to upstream circuit breaker. Replace with new Service Interface.
Check that pins of seven-pin test cable have not been bent, pushed in, pulled out or otherwise damaged.
Refer to MicroLogic Trip Unit Compatibility to determine if test is applicable to trip units.

If both upstream and downstream trip units are powered and trip indicator LEDs are not flashing, verify wiring between devices.

Terminal Z1 from downstream trip unit must be connected to terminal Z3 of upstream trip unit.
Terminal Z2 of downstream trip unit must be connected to terminals Z4 (for short time) and Z5 (for ground fault) of upstream trip unit.

If wiring is correct and trip indicators do not flash while Service Interface is initiating ZSI test, then verify trip unit is not self-restrained. Use an ohmmeter to verify terminal Z3 is not shorted to terminals Z4 and/or Z5. All devices are factory-shipped in self-restrained configuration with Z3 shorted to Z4 and Z5.

If system includes Restraint Interface Module (RIM) module, push-to-test button sends a ZSI test signal to upstream devices. For correct wiring and operation instructions, refer to the RIM Instruction Bulletin.